This investigation of the short-term as well as the long-term effects of contact lens wear on the cornea includes specular microscopy studies of changes in corneal curvature, corneal epithelial morphology, and corneal endothelial cell morphology. Analysis of the data obtained will help us understand the dynamics involved in the interaction between a contact lens and the cornea, the risk to corneal tissues, and how a systemic or local disorder may increase these risks. In addition, we are studying the differences in corneal endothelial status of wearers of soft compared with hard contact lenses. Animal models showing corneal endothelial abnormalities similar to those in long-term contact lens wearers also are being explored in diabetic and galactosemic animal models. Treatment with aldose reductase inhibitors helps prevent these corneal abnormalities.